Field of the Invention
The present invention relates to golf balls. Specifically, the present invention relates to improvement of aerodynamic characteristics of golf balls.
Description of the Related Art
Golf balls have a large number of dimples on the surfaces thereof. The dimples disturb the air flow around the golf ball during flight to cause turbulent flow separation. This phenomenon is referred to as “turbulization”. Due to the turbulization, separation points of the air from the golf ball shift backwards leading to a reduction of drag. The turbulization promotes the displacement between the separation point on the upper side and the separation point on the lower side of the golf ball, which results from the backspin, thereby enhancing the lift force that acts upon the golf ball. Excellent dimples efficiently disturb the air flow. The excellent dimples produce a long flight distance.
JPH5-103846 discloses a golf ball which has dimples the diameters, the depths, and the number of which are made appropriate.
U.S. Pat. No. 5,782,703 (JPH10-43342) discloses a golf ball which has dimples the ratio of the diameter and the depth of each of which is made appropriate.
U.S. Pat. No. 5,782,702 (JPH10-43343) discloses a golf ball in which the ratio of the volumes of dimples relative to the volume of the ball is made appropriate.
JP2000-107338 discloses a golf ball having a diameter and a weight which are made appropriate.
When a golf ball is hit at the vicinity of the center of the face of a club head, the kinetic energy of the club head is sufficiently transferred to the golf ball. With this hit, the spin rate of the golf ball is generally appropriate.
A hitting point on a face varies at each shot. In particular, the hitting point greatly varies at each shot of an amateur golf player. The variation in hitting point causes variation in spin rate.
In a conventional golf ball, the specifications of dimples are determined such that a large flight distance is achieved under an appropriate spin rate condition. With the golf ball, a large flight distance is not achieved when a spin rate is not appropriate. In the golf ball, variation in hitting point causes variation in spin rate, and the variation in spin rate causes variation in flight distance. A golf player who uses a golf ball having great variation in flight distance has difficulty in causing the golf ball to stop at a target point.
Golf players desire golf balls having less flight distance's dependency on a spin rate. In other words, golf players desire golf balls having excellent flight distance stability. An object of the present invention is to provide a golf ball having excellent flight distance stability.